Research And Application Of Digital Image Detection Algorithm Based On Tubing Crack

In the process of oil and gas exploitation and transportation, pipeline as a important means of transport, with the increase of pipelines’ working time, the tubing becomes aging, the emergence of the pipeline crack threatening the safety of its operation at any time. Tubing crack detection is important means to check the state of the tubing, so study a kind of suitable for tubing crack detection algorithm has great significance. This thesis research a large number of pipeline crack detection development present situation at home and abroad, On the one hand, the traditional tubing crack nondestructive testing methods, such as ultrasound test, leakage magnetic field test, eddy current test and so on. analysis the advantages and shortcomings of them; on the other hand, this thesis introduces the digital image detection method in the application of crack detection, such as steel plate crack detection, glass crack detection and so on, which proves that the digital image detection algorithm in the pipeline crack detection probability. Based on these two points is put forward for the first time detection algorithm of digital image processing was applied to pipeline crack detection.According to the characteristics of oil pipe crack image, this thesis first discussed the technology of digital image preprocessing and select the image grayscale, histogram equalization combined with logarithmic transformation and wavelet denoising, Then the traditional algorithms of image edge detection was applied to pipeline crack detection, and analysis of the test result under the MATLAB simulation. On this basis, the research is mainly focused on the improved Canny operator and test method of mathematical morphology in the application of the tubing.The improved Canny pipeline crack detection algorithm, aiming at the defects of the traditional Canny operator, combining the actual situation of oil pipe crack image, choose a gradient calculation, the threshold selection and edge connection ways of improving Canny operator. Under the MATLAB simulation, it can make better effect on pipeline crack detection than other traditional testing method, but it remains to be improved.The improved morphological tubing crack detection algorithm, witch involved in hot-hat transform, in view of the defect that the traditional edge method using the single symmetrical structure elements, it chooses the method of structural elements can be divided into several different angles. Through experiment contrast, found that the improved algorithm can suppress noise better and guarantee the continuity of the oil pipe crack at the same time.